First, mining is decentralized!
https://blockchain.info/pools just because it is not a commie "equal share to all proletariate" the hashing power is in fact distributed (every pool mine has thousands of individual, group, corporate etc miners!), changing hands over time, can be freely entered or left (!).
Mining is
physically centralized and that is a problem which will only get worse as mining concentrates in the areas with the cheapest electricity or best thermodynamic advantage.
evolution...
Bitcoin is more like a Game of Life than evolution specifically.